Plastic bowling pin comprising an extruded tubular body member



July 4, 1967 g 3,329,430'

Y ME

PLASTI LING PIN COM ING AN EXTR ED TUBULAR BOD MBER Filed Dec. 27, 1963 2 Sheets-Sheet l Fig-3 VENTOR HA .H. WANDERS July 4, 1967 H. H. WANDERS 3,329,430 PLASTIC DBECgILING PIN COMPRJE TUBULAR BODY S ING AN MBER 2 Sheets-Sheet 2 EXTRU Filed Dec. 27 1963 INVENTOR HANS H. WANDERS BY 5mm (j ATTO EYS United States Patent 3,329,430 PLASTEC BOWLING PIN COMPRISING AN EXTRUDED TUBULAR BODY MEMBER Hans H. Wanders, Hingham, Mass, assignor to Garland Manufacturing Company, Saco, Maine, a corporation of Maine Filed Dec. 27, 1963, Ser. No. 333,810 12 Claims. (Cl. 27382) This application is a continuation-in-part of my copending application Serial No. 239,632, filed Nov. 23, 1962, for Composition Bowling Pin, now Patent No. 3,231,274.

This invention relates to bowling pins.

Although the invention is not limited thereto, one illustrative embodiment of bowling pin is one for candlepin bowling, which is popular in some areas. Such a pin is of an elongated barrel or double tapered shape which is symmetrical about a transverse mid-plane. Candlepins have long been made of wood, such as maple. Wooden pins, however, have a rather short life by reason, among others, of the manner in which the game is played. Although in the games of tenpins and duckpins the so-called deadwood or fallen pins are removed from the bowling alley after each ball has been rolled, in candlepin bowling only the pins which lie wholly in the gutter are removed. The bowler in delivering a second or third ball plays both the standing and the fallen pins. This frequently subjects the fallen pins to blows delivered either by the ball or by contact with other pins directly upon or near their end surfaces. When the pins are made of wood, the end grain is exposed at the end of the pin. Consequently, candlepins are frequently splintered at their ends and thus require replacement. Wooden bowling pins of all types are also subject to denting which is aggravated by successive blows in the same area and results in eventual splintering or splitting of the pins.

In order to overcome the inherent disadvantages of wooden bowling pins, it has been proposed to make bowling pins with a wooden core having thin plastic coatings thereon. Such plastic-coated wooden pins, however, have not been satisfactory, since the plastic coating tends to chip and peel after only a relatively short use of the pins. This is caused primarily by local compression or denting of the wooden core following impact with a ball or other pins. This tends to leave a space between the thin plastic coating and the wooden core so that eventually the plastic coating is loosened over substantial areas of the surface of the pin.

The invention has among its objects the provision of a novel bowling pin which is characterized by its freedom from damage and breakage in normal use and consequently by its long useful life.

Other objects of the invention reside in the provision of a novel bowling pin made of plastic material, a novel hollow bowling pin and a hollow plastic bowling pin incorporating novel end closure means.

A further object is to provide a novelly constructed plastic bowling pin which meets all of the regulatory requirements of the game and constitutes an acceptable substitute for the wooden pins now in common use.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

FIG. 1 is a view in perspective of one embodiment of a bowling pin of the candlepin type made in acocrdance with the invention;

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FIG. 2 is a fragmentary view on an enlarged scale in vertical axial section taken on line 22 of FIG. 1, the end closing plug being shown in elevation;

FIGS. 3 and 4 are fragmentary views similar to FIG. 2 showing additional embodiments of the invention, the end closure means in FIG. 3 being partly broken away and the end closure means in FIG. 4 being shown in section;

FIG. 5 is an elevation view of a tenpin or duckpin type bowling pin made in accordance with the invention;

FIG. 6 is an enlarged scale fragmentary view in vertical axial section taken on line 66 of FIG. 5; and

FIG. 7 is a schematic sectional view of an apparatus adapted for use in making a pin in accordance with the invention.

The illustrative bowling pin of FIGS. 1 and 2, which is of the candlepin type, is generally designated by the reference character 10. Such pin is hollow, generally of elongated barrel shape and symmetrical about a mid-horizontal plane. The pin 10 thus may be stood vertically upon 7 either of its transverse end surfaces 11. The body of pin 10 is made of generally tubular form, the passage through the pin being closed at both ends by plugs 12 which form a part of the total pin. The illustrative pin is provided with a broad, shallow groove 13 mid-way of its length within .1 l which an identifying and indictaing band made, for example, of colored plastic tape may be located.

The body of pin 10 is, as explained, of generally tubular shape with the outer surface somewhat tapered adjacent each end. The wall of such body is designated 14, and the longitudinal passage through the body is designated 15. At each end of body 14 there is an axially directed centrally disposed counterbore 17 which has a diameter somewhat greater than that of the wall 16 of passage 15. At the inner end of the counterbore the body of the pin is provided with an annular internal groove generally designated 19 by means of which the plug 12 is lockingly retained within the end of the passage 15, 17 in a manner to be described. The groove 19 has a circular cylindrical wall portion 20, an upper radial shoulder 21 and a lower radial shoulder 18. The plug 12 has an elongated circular cylindrical outer portion or body 22 and an enlarged head or flange generally designated 24 which is adapted lockingly to be received within groove 19.

In an illustrative embodiment, the relaxed shape and dimensions of head or flange 24 of the plug are the same or substantially the same as those of groove 19. As shown, the inner edge corner of flange 24 may be peripherally chamfered, as at 23, to facilitate entry of the plug into bore 17 during assembly. If desired, the mouth of bore 17 may be chamfered for this purpose instead of flange 24, in which case the end of the pin and plug may be machined after assembly to provide a flat end surface 11. The maximum diameter of body portion 22 of the plug is likewise the same or substantially the same as the diameter of the counterbore 17. Thus, in an illustrative pin the diameter of body 22 of the plug is the same as the diameter of the counterbore 17 and may, for example, equal about 1 7 inches. The maximum diameter of flange portion 24 of the head of plug 12 is substantially the same as the diameter of wall portion 20 of groove 19 and may equal about 1% inches. The smaller or inner diameter of the frusto-conical chamfer 23 of plug 12 may be about 1 /2 inches and thus sufliciently great to insure a good seating of the inner transverse face of plug 12 on shoulder 18. The body 14 of pin 10 and the plug 12 are preferably made of strong, stiff, but somewhat resilient plastic.mate rial, such as a high impact, high density polyethylene having a very high molecular weight. Suitable materials having specific gravities of 0.940 to 0.942 are marketed by Hercules Powder Company as Hi-Fax 1900 series.

3 The average molecular weight of this material is estimated to be over,2,000,000.

The plugs 12 may be assembled in the body 14 of the pin by placing a plug upon the still open end of the pincoaxially thereof and then thrusting it into counterbore 17 of the pin with an arbor press or the like having a movable plungeror platen. During such thrusting of the plug into place, the frusto-conical portion 23 of the head of the plug acts asa centering and locating pilot to guide the plug into counterbore 17. During such insertion of the plug at room temperature, the counterbore 17 of the pin body is slightly stretched or distorted to allow the somewhat larger head of the plug to progressively enter the counterbore. After the plug has reached the fully inserted position shown in FIG. 2, the resilience of the pin body around bore 17 restores it to its relaxed original size and shape so that the plug is firmly secured against escape from the pin body by shoulder 21 and against further insertion into bore 15 by shoulder 18. The plug is also held in place by the gripping action. Preferably, the wall of counterbore 17 is slightly tapered or cone-like, the outer end thereof having a diameter several thousandths, say 0.010, of an inch less than the diameter near shoulder 21 and less than the diameter of plug body 22. Thus, when the body portion 14 relaxes about plug body 22, the latter is compressively gripped in the vicinity of the end surface 11. This gripping action, as well as the friction between the walls of counterbore 17 and plug body 22, assists in securing the plug against movement relative to the pin body.

The pin body 14 may be formed in a number of ways. Thus, with some plastic materials, the body may be molded, slightly over-size if desired, and may then be finished ordressed to final shape and dimensions, as by grinding or turning. Alternatively, the bodies of the pins, particularly those made of Hercules 1900 series high molecular weight polyethylene which is exceedingly difficult to mold may be formed in a novel manner by first molding the plastic material in the form of a continuous relatively heavy-walled tube which is then cut into suitable lengths .for further processing. From some materials, the heavy-walled tubing may be extruded in a known manner. The diameter of the bore 15 in the thus molded or extruded tube and the wall thickness thereof are calculated to provide a finished bowling pin having regulation weight and outside dimensions. The counterbore 17 and groove 19 at each end of a cut length of the tubing are then coaxially formed in any suitable known manner by cutting or turning operations. The rounded barrel-shape outer surface of body 14 is imparted to the finished pin body by removing stock from the outer periphery of the each of the illustrated embodiments may have the inner ends thereof counterbored as at 32 (FIG. 3). This may be done to reduce weight, to adjust the balance of the total pin or to facilitate insertion of the plug into the pin body, particularly when a deeper retaining flange 24 is employed.

In a further embodiment shown in FIG. 4, the outer end of the closure plug 12" is of reduced diameter to form a cylindrical post 33 which is partially within and projects outwardly beyond the outer end of counterbore 17 to thereby form an annular channel 34. An annular tip piece or ring comprises a cylindrical portion 35 having a press fit in channel 34 and a radial end flange 36 seated on the end of pin body 14. If desired, the outer end of post 33 may be slightly radially expanded by striking the same axially and centrally thereof with a cone-shaped swaging tool to thereby more securely anchor the tip piece in' channel 34.

p A tenpin or duckpin type bowling pin as illustrated in FIGS. 5 and 6 may be constructed in the same manner as described above for candlepins, except that the closure plug 42 in the upper end of the main hollow body 44 of tube by suitable means, such as by turning on a lathe.

For this operation the tube may be centered and supported by providing a tail stock bearing on the lathe which fits into the counterbore 17, thereby assuring concentricity of the counterbore and the outer surface of the finished body.

The plugs 12 may be made of any suitable material, but the same are. preferably made of a sturdy plastic material which may be the same as that used in the body portion ,14. Some plastics may be injection or compression molded to the desired dimensions or the plugs may 7 be machined to the proper dimensions from molded bar stock or slugs. High density polyethylene and nylon marketed as No. 69 Zytel are examples of suitable materials for making the end closure plugs.

In the embodiment of FIG. 2, end closure plug 12 completely fills the counterbore 17 and the ends of the pin body and plug are flush, thereby forming the transverse end surface 11 of the total pin. As shown in FIG. 3, the end closure plug 12 may be provided with an integral flange 30 which engages the annular end surface of the pin body and has a peripheral surface 31 tapered and filleted to form a suitable continuation of the outer surface of the pin body 14. The end closure plugs of the pin is extended upwardly to form the integral neck 45 and head portion 46 of the total pin. This upper body portion 45, 46 may be either solid or hollow for weight distribution or other purposes. The bottom closure plug 43 may be made and assembled in accordance with any of the embodiments of FIGS. 2 to 4. The hollow body 44 may be made in the same manner as candlepin body 14, except that the outer surface is machined to the proper dimensions and shape to provide a conventional regulation tenpin or duckpin.

The novel method contemplated for making the hollow body portion of the bowling pin above described comprises a novel continuous method or process of molding tubing from thermoplastic materials, especially from materials having high molecular weight, such as the aforesaid Hi-Fax 1900 series polyethylene. This method may be carried out with the novel apparatus schematically illustrated in FIG. 7. As shown, the apparatus comprises a heating or melting chamber 50 in which a plunger 51 is mounted for reciprocation. An inlet hopper or supply opening 52 adapted to be opened and closed by piston 51 is provided for feeding measured charges of powdered or flaked thermoplastic material 53 into the chamber. This material may be pre-heated in the hopper if desired. A centrally disposed outlet from chamber 50 is provided in the form of a central runner or passage 54, the delivery end of which opens into one end of a transverse runner or cylindrical injection pot 55.

The inlet or receiving end of chamber 50 is preferably connected to runner 54 by a plurality of circularly arranged, restrictive passages or runners 63, wherein the thermoplastic mixture will be more easily and uniformly heated by external heating means. The solid structure surrounded by passages 63 terminates in chamber 50 in the form of a cone to direct the material 53 into said passages when the plunger 51 moves to the right beyond entrance 52. Passages 63 merge at the discharge ends thereof into central runner 54.

The delivery end of injection or spreader pot 55 is provided with a plurality of equally spaced circularly arranged holes or orifices 56 which open into an elongated tubular mold 57 around a centrally disposed rod or core 58 having its inner end supported by the partition or disc 64 in which cavity 55 and passages 56 are formed. The heating chamber 50, the disc 64 and mold 57 may be secured together by any suitable known means, such as by bolts through flanges thereon.

The outer end of mold 57 is open for continuously dispensing or discharging the molded tubing. At the beginning of a molding operation before the leading end of the molded tube reaches the exit end of mold 57, the free end of rod 58 may be supported by any suitable means, such as by a cylindrical Weight 59 shown by dotted lines. The

latter may be sufiiciently heavy to retard the fiowable plastic material initially injected into the mold until the latter has been completely filled and the leading end of the molded tube projects from the mold and beyond the end of rod 58. In some instances it may be desirable to produce a solid bar rather than a tube, in which case the rod or core 58 may be removed and the passage in mold 57 may have any desired cross-section.

Any suitable means may be provided for heating chamber 50, injection pot 55 and the receiving end of mold 57, such as the electrically energized heating bands 60* and 61. Means, such as a cooling coil 62, are provided for reducing the temperature of the outer or delivery end portion of mold 57 and the molded tubing or bar which passes therethrough.

In one suitable apparatus for molding thick-walled tubing from Hi-Fax" 1900 series polyethylene mixed with a suitable quantity of an antioxidant for use in making candlepin bodies 14, the heating chamber or injection :ylinder 50 has a diameter of about 3%; inches and a capacity of about 32 to 36 ounces of the raw materials 53 and the chamber is heated by heating bands 60 to a temperature between 400 F. and 450 F. for reducing the raw material mixture to a fiowable or plasticized state. The desired viscosity of the material and, hence, the times and temperature used will depend upon the nature of the material. There are twelve one-half inch passages 63 and runner 54 of such apparatus has a diameter of about inch. There are six orifices 56, each having a diameter of about %-inch connecting injection pot 55 with the receiving end of mold 57. The latter has a length of approximately four feet and is heated at its receiving end to a temperature of about 400 F. by bands 61. The plunger 51 applies pressure impulses of about 1,000 psi. to the materials in chamber 50 at thirty second intervals and about four ounces of raw materials 53 are added through inlet 52 after each pressure impulse. The frequency of the pressure impulses and the rate at which new materials are added to chamber 50 determine the speed at which the molded tubing is fed through mold 57. The movement of the tubing through the mold, which is heated at its receiving end and cooled at its delivery end, should be at a speed such that the molded tube is gradually cooled to a temperature below the set-up temperature of the molded material, that is, about 240 F., and preferably to a temperature of about 120 F. at the open end of mold 57. That portion of the molded tube within the elongated mold 57 functions somewhat as a stopper so that the heated material or portion of the molded tube near the input end of the mold and the material in pot 55 are maintained under a substantially and sufliciently constant pressure to insure a sound and solid molded wall structure in the molded tubing. Tubing of any desired length may thus be produced and later cut into suitable lengths for conversion into bowling pin bodies in the manner above described by drilling the counterbores 17 therein and turning the outer surfaces thereof down to the desired dimensions and shape.

There are thus provided novel bowling pins which may be made wholly or in part of thermoplastic materials that are sturdy and highly resistant to shock and abrasion when subjected in use to repeated substantial stresses and impact. Bowling pins made in accordance with the invention have superior toughness and impact strength as compared to pins heretofore used. The novel bowling pins of the invention have a useful life many times greater than the conventional wooden pins heretofore used. The novel method contemplated for molding tubing of thermoplastic materials, such as high molecular Weight polyethylene, insures a sound molded tube having suitably uniform physical characteristics for conversion into improved bowling pin bodies. There is also provided novel apparatus for practicing said method.

Although only a limited number of embodiments or modifications of the invention have been illustrated in the drawings and described in the foregoing specification,

it is to be expressly understood that the invention is not limited thereto. Various changes may be made in the specific designs and in the arrangement of parts illustrated without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. A bowling pin comprising an extruded and externally machined main body member of substantially rigid but slightly resilient thermoplastic material having a central bore with an enlarged cylindrical counterbore at an end thereof and an annular internal groove at the inner end of the counterbore, said member having structural characteristics resulting from the formation thereof by an extrusion process and said material having an average molecular weight in excess of about two million, and a unitary end closure member of substantially rigid material seated on the internal shoulder at said inner end of the counterbore and having a cylindrical body portion tightly fitting the counterbore and radially extending annular flange means projecting into said groove, whereby said closure member and said body member are interlocked against relative axial movement in either direction.

2. A bowling pin as defined in claim 1, wherein said body portion of the closure member completely fills said counterbore and has an outer end surface flush with the end surface of said main body member.

3. A bowling pin as defined in claim 1, wherein said closure member has a recess within the inner end thereof surrounded by said radially extending flange means on the closure member.

4. A bowling pin as defined in claim 1, wherein said closure member has an external flange at the outer end thereof engagaing the annular end surface of said main body member.

5. A bowling pin as defined in claim 1, wherein said closure member has an outer end part having a diameter less than the diameter of the counterbore, and a rigid ring having a force fit into the annular space between said outer end part of the closure member and the wall of the counterbore.

6. A bowling pin as defined in claim 5, wherein said ring comprises a flanged end portion surrounding said outer end part of the closure member and engaging the annular end surface of said main body member, the outer end of said ring being flush with the outer end part of the closure member to form the transverse end surface of the bowling pin.

7. A bowling pin comprising a tubular one-piece extruded body member of thermoplastic material having structural characteristics resulting from the formation thereof by an extrusion process and further having an enlarged counterbore in each end thereof and an internal annular groove at the inner end of each counterbore, and closure means for each end of said member comprising a unitary end closure plug having a cylindrical body part closely fitting said counterbore and a radially enlarged annular part extending radially into said groove in interlocking relation with said body member, whereby said plugs are held against axial movement in either direction relative to said body member.

8. A bowling pin as defined in claim 7 wherein said thermoplastic material has an average molecular weight of at least about two million 9. A bowling pin comprising a tubular one-piece extrudede body member of thermoplastic material which is substantially rigid but slightly resilient at room temperature and has an average molecular weight in excess of approximately two million, said member having an internal annular groove in the bore thereof spaced inwardly from an end thereof and said member having structural characteristics resulting from the formation thereof by an extrusion process, and means inserted into and closing an end of said bore comprising a unitary end closure member having a cylindrical body portion closely fitting said bore and an enlarged annular part extendingradially into said groove in interlocking relation with said body member, whereby as a result of said interlocking relation said closure member is held against axial movement in either direction relative to said body member.

10. A bowling pin as defined in claim 9 wherein said material is polyethylene.

11. A bowling pin as defined in claim 9, wherein said body portion of the closure member completely fills the outer end of said bore and terminates transversely flush with the end surface of said body member.

12. A bowling pin comprising a substantially rigid one-piece extruded plastic body member with an axial passage therethrough, said member having structural characteristics resulting from the formation thereof by an extrusion process from thermoplastic material having an average molecular weight of at least approximately two million, and means at the ends of the body member forming closures for said passage, each said closure being constituted by a unitary substantially rigid plug closely fitting the outer end of said passage and retained in the 20 latter solely by the interlocking. of an annular radially projecting flange on said plug and a radially extending internal annular groove in the wall of said axial passage through said body member.

References Cited UNITED STATES PATENTS 11/1924 Lemieux et al 273-82 2/ 1955 DiPierro 27382 3/1956 Brinkmann 273-82 12/1956 Schroeder et al. 27382 6/1964- Bilodeau l56-98 7/1964 Dosker 156-213 11/1964 Weissman et a1. 273-82 2/1965 Ernst 27382 4/1965 Ernst 27382 6/1965 Hebble 27382 7/1965 Cariani 273--82 8/1965 Halip 27382v 1/1966 Wanders 273-82 2/1966 Conklin et a1. 273-82 5/1966 Craig et -al. 27382 FOREIGN PATENTS 11/ 1956 Germany.

DELBERT B. LOWE, Primary Examiner. 

7. A BOWLING PIN COMPRISING A TUBULAR ONE-PIECE EXTRUDED BODY MEMBER OF THERMOPLASTIC MATERIAL HAVING STRUCTURAL CHARACTERISTICS RESULTING FROM THE FORMATION THEREOF BY AN EXTRUSION PROCESS AND FURTHER HAVING AN ENLARGED COUNTERBORE IN EACH END THEREOF AND AN INTERNAL ANNULAR GROOVE AT THE INNER END OF EACH COUNTERBORE, AND CLOSURE MEANS FOR EACH END OF SAID MEMBER COMPRISING A UNITARY END CLOSURE PLUG HAVING A CYLINDRICAL BODY PART CLOSELY FITTING SAID COUNTERBORE AND A RADIALLY ENLARGED ANNULAR PART EXTENDING RADIALLY INTO SAID GROOVE IN INTERLOCKING RELATION WITH SAID BODY MEMBER, WHEREBY SAID PLUGS ARE HELD AGAINST AXIAL MOVEMENT IN EITHER DIRECTION RELATIVE TO SAID BODY MEMBER. 